Transmission symbols mapping for antenna diversity

ABSTRACT

Methods and apparatus for transmitting data via multiple antennas by using antenna diversity. A transmission diversity scheme is established such that two transmission matrices that are in accordance with the space frequency block code combined with Frequency switched transmit diversity (SFBC+FSTD) scheme, are alternatively applied in either the frequency domain, or the time domain, or both of the frequency domain or then time domain. The symbols in the transmission matrices may be transmitted either as one burst in a primary broadcast channel (PBCH), or as discrete bursts in the primary broadcast channel.

CLAIM OF PRIORITY

This application makes reference to, claims all benefits accruing under35 U.S.C. §119 from, and incorporates herein a U.S. ProvisionalApplication entitled TRANSMISSION SYMBOLS MAPPING FOR ANTENNA DIVERSITYfiled in the U.S. Patent & Trademark Office on 6 Jun. 2007 and thereduly assigned Ser. No. 60/924,942.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for mapping transmissionsymbols into transmission resources in a communication system in orderto utilize antenna diversity.

2. Description of the Related Art

A typical cellular radio system includes a number of fixed base stationsand a number of mobile stations. Each base station covers a geographicalarea, which is defined as a cell.

Typically, a non-line-of-sight (NLOS) radio propagation path existsbetween a base station and a mobile station due to natural and man-madeobjects disposed between the base station and the mobile station. As aconsequence, radio waves propagate while experiencing reflections,diffractions and scattering. The radio wave which arrives at the antennaof the mobile station in a downlink direction, or at the antenna of thebase station in an uplink direction, experiences constructive anddestructive additions because of different phases of individual wavesgenerated due to the reflections, diffractions, scattering andout-of-phase recombination. This is due to the fact that, at highcarrier frequencies typically used in a contemporary cellular wirelesscommunication, small changes in differential propagation delaysintroduces large changes in the phases of the individual waves. If themobile station is moving or there are changes in the scatteringenvironment, then the spatial variations in the amplitude and phase ofthe composite received signal will manifest themselves as the timevariations known as Rayleigh fading or fast fading attributable tomultipath reception. The time-varying nature of the wireless channelrequire very high signal-to-noise ratio (SNR) in order to providedesired bit error or packet error reliability.

The scheme of diversity is widely used to combat the effect of fastfading by providing a receiver with multiple faded replicas of the sameinformation-bearing signal.

The schemes of diversity in general fall into the following categories:space, angle, polarization, field, frequency, time and multipathdiversity. Space diversity can be achieved by using multiple transmit orreceive antennas. The spatial separation between the multiple antennasis chosen so that the diversity branches, i.e., the signals transmittedfrom the multiple antennas, experience fading with little or nocorrelation. Transmit diversity, which is one type of space diversity,uses multiple transmission antennas to provide the receiver withmultiple uncorrelated replicas of the same signal. Transmissiondiversity schemes can further be divided into open loop transmitdiversity and closed-loop transmission diversity schemes. In the openloop transmit diversity approach no feedback is required from thereceiver. In one type of closed loop transmit diversity, a receiverknows an arrangement of transmission antennas, computes a phase andamplitude adjustment that should be applied at the transmitter antennasin order to maximize a power of the signal received at the receiver. Inanother arrangement of closed loop transmit diversity referred to asselection transmit diversity (STD), the receiver provides feedbackinformation to the transmitter regarding which antenna(s) to be used fortransmission.

An example of open-loop transmission diversity scheme is the Alamouti2×1 space-time diversity scheme. The Alamouti 2×1 space-time diversityscheme contemplates transmitting a Alamouti 2×2 block code using twotransmission antennas using either two time slots (i.e., Space TimeBlock Code (STBC) transmit diversity) or two frequency subcarriers(i.e., Space Frequency Block Code (SFBC) transmit diversity).

One limitation of Alamouti 2×1 space-time diversity scheme is that thisscheme can only be applied to two transmission antennas. In order totransmit data using four transmission antennas, a Frequency SwitchedTransmit Diversity (FSTD) or a Time Switched Transmit Diversity (TSTD)is combined with block codes.

The problem with combined SFBC+FSTD scheme and STBC+TSTD schemes is thatonly a fraction of the total transmission antennas and hence poweramplifier capability is used for transmission in a given frequency ortime resource. This is indicated by ‘0’ elements in the SFBC+FSTD andSTBC+TSTD matrix given above. When the transmit power on the non-zeroelements in the matrix is increased, bursty interference is generated tothe neighboring cells degrading system performance. Generally, burstyinterference manifests itself when certain phases of a frequency hoppingpattern incur more interference than other phases.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide animproved method and transmitter circuit for transmitting data viamultiple antennas.

It is another object to provide a method and transmitter circuit fortransmitting data by using multiple antennas transmission diversityscheme.

According to one aspect of the present invention, a transmit diversityscheme is established for four symbols S₁, S₂, S₃ and S₄ such that twotransmission matrices T₁ and T₂ are alternatively applied in a frequencydomain. The two transmission matrices T₁ and T₂ are respectivelyestablished by:

${T_{1} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = \begin{bmatrix}S_{1} & S_{2} & 0 & 0 \\{- S_{2}^{*}} & S_{1}^{*} & 0 & 0 \\0 & 0 & S_{3} & S_{4} \\0 & 0 & {- S_{4}^{*}} & S_{3}^{*}\end{bmatrix}}},{and}$ ${T_{2} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = \begin{bmatrix}S_{3} & S_{4} & 0 & 0 \\{- S_{4}^{*}} & S_{3}^{*} & 0 & 0 \\0 & 0 & S_{1} & S_{2} \\0 & 0 & {- S_{2}^{*}} & S_{1}^{*}\end{bmatrix}}},$where T_(ij) represents the symbol to be transmitted on the ith antennaand the jth subcarrier.

The second row and the third row of each of the transmission matrices T₁and T₂ may be exchanged, such that the symbols on the second row of eachof the transmission matrices T₁ and T₂ are transmitted via the thirdantenna, and the symbols on the third row of each of the transmissionmatrices are transmitted via the second antenna.

The four symbols may be repeatedly transmitted in the frequency domainfor two times, such that one of the two transmission matrices T₁ and T₂is applied to the first transmission, and the other one of the twotransmission matrices T₁ and T₂ is applied to the second transmission.

Alternatively, the four symbols may be repeatedly transmitted in thefrequency domain for N times, with N being a positive number and N>1,such that one of the two transmission matrices T₁ and T₂ is applied toodd numbered transmissions, and the other one of the two transmissionmatrices T₁ and T₂ is applied to even numbered transmissions. Inaddition, the first through (N−1)-th transmissions may be fullrepetitions, and the N-th transmission may be a partial repetition.

The four symbols may be transmitted as a burst of signal in a primarybroadcast channel, with the transmission being in accordance with thetransmit diversity scheme.

According to another aspect of the present invention, a transmitdiversity scheme is established for four symbols S₁, S₂, S₃ and S₄, byalternatively applying two transmission matrices T₁ and T₂ in a timedomain.

The four symbols may be repeatedly transmitted in the time domain fortwo times, such that one of the two transmission matrices T₁ and T₂ isapplied to the first transmission in a first time slot, and the otherone of the two transmission matrices T₁ and T₂ is applied to the secondtransmission in a second time slot.

The symbols in both of the first time slot and the second time slot maybe transmitted as one burst of signal in a primary broadcast channeltransmission, with the first time slot and the second time slot beinglocated within the same subframe.

Alternatively, the symbols in the first time slot may be transmitted asa first burst of signal in a primary broadcast channel transmission, andthe symbols in the second time slot may be transmitted as a second burstof signal in the primary broadcast channel transmission, with the firstburst and the second burst being separated by a certain time interval.

According to yet another aspect of the present invention, a transmitdiversity scheme is established for four symbols S₁, S₂, S₃ and S₄ byalternatively applying two transmission matrices T₁ and T₂ in both of atime domain and a frequency domain.

The four symbols may be repeatedly transmitted over eight subcarriersand two time slots. In a first time slot, a first one of thetransmission matrix matrices T₁ and T₂ is applied to the first foursubcarriers, and a second one of the transmission matrix matrices T₁ andT₂ is applied to the last four subcarriers. In a second time slot, thesecond one of the transmission matrix matrices T₁ and T₂ is applied tothe first four subcarriers, and the first one of the transmission matrixmatrices T₁ and T₂ is applied to the last four subcarriers.

The symbols in the first and second time slots may be transmitted as oneburst of signal in a primary broadcast channel transmission, with thefirst time slot and the second time slot being located within the samesubframe.

Alternatively, the symbols in the first time slot may be transmitted asa first burst of signal in a primary broadcast channel transmission, andthe symbols in the second time slot may be transmitted as a second burstof signal in the primary broadcast channel transmission, with the firstburst and the second burst being separated by a certain time interval.

Still alternatively, the four symbols may be repeatedly transmitted forfour times over eight subcarriers four time slots, such that: in a firsttime slot, a first one of the transmission matrix matrices T₁ and T₂ isapplied to the first four subcarriers; in a second time slot, a secondone of the transmission matrix matrices T₁ and T₂ being applied to thelast four subcarriers; in a third time slot, the first one of thetransmission matrix matrices T₁ and T₂ being applied to the first foursubcarriers; and in a fourth time slot, the second one of thetransmission matrix matrices T₁ and T₂ being applied to the last foursubcarriers.

According to still another aspect of the present invention, when a firstburst of signal and a second burst of signal is received within a radiosubframe, the second burst of signal is decoded by applying a firstspace frequency block code format containing a transmission matrix T₁.If the second burst of signal is not successfully decoded, the firstburst of signal and the second burst of signal are softly combined togenerate a combined signal which is then decoded by applying the firstspace frequency block code format to the first burst of signal, andapplying a second space frequency block code format containing atransmission matrix T₂ to the second burst of signal. If the combinedsignal is not successfully decoded, the second burst of signal isbuffered.

According to still yet another aspect of the present invention, atransmit diversity scheme is established for four symbols S₁, S₂, S₃ andS₄ by alternatively applying two transmission matrices T₁ and T₂ in afrequency domain and/or a time domain. The two transmission matrices T₁and T₂ are respectively established by:

${T_{1} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = {\frac{1}{\sqrt{4}}\begin{bmatrix}S_{1} & {- S_{2}^{*}} & S_{1} & {- S_{2}^{*}} \\S_{2} & S_{1}^{*} & S_{2} & S_{1}^{*} \\S_{3} & {- S_{4}^{*}} & {- S_{3}} & S_{4}^{*} \\S_{4} & S_{3}^{*} & {- S_{4}} & {- S_{3}^{*}}\end{bmatrix}}}},{and}$ ${T_{2} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = {\frac{1}{\sqrt{4}}\begin{bmatrix}S_{1} & {- S_{2}^{*}} & S_{1} & {- S_{2}^{*}} \\S_{3} & {- S_{4}^{*}} & {- S_{3}} & S_{4}^{*} \\S_{2} & S_{1}^{*} & S_{2} & S_{1}^{*} \\S_{4} & S_{3}^{*} & {- S_{4}} & {- S_{3}^{*}}\end{bmatrix}}}},$where T_(ij) represents the symbol to be transmitted on the ith antennaand the jth subcarrier.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention, and many of the attendantadvantages thereof, will be readily apparent as the same becomes betterunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings in which likereference symbols indicate the same or similar components, wherein:

FIG. 1 schematically illustrates an Orthogonal Frequency DivisionMultiplexing (OFDM) transceiver chain suitable for the practice of theprinciples of the present inventions;

FIG. 2 schematically illustrates a Space Time Block Code transmissiondiversity scheme for two transmission antennas;

FIG. 3 schematically illustrates a Space Frequency Block Codetransmission diversity scheme for two transmission antennas;

FIG. 4 schematically illustrates an alternative Space Frequency BlockCode transmission diversity scheme for two transmission antennas;

FIG. 5 schematically illustrates mapping of downlink reference signalsin a contemporary 3^(rd) Generation Partnership Project Long TermEvolution system;

FIG. 6 schematically illustrates a Space Frequency Block Code combinedwith Frequency Switched Transmit Diversity (SFBC+FSTD) scheme as oneembodiment according to the principles of the present invention;

FIG. 7 schematically illustrates another Space Frequency Block Codecombined with Frequency Switched Transmit Diversity (SFBC+FSTD) schemeas another embodiment according to the principles of the presentinvention;

FIG. 8 schematically illustrates still another Space Frequency BlockCode combined with Frequency Switched Transmit Diversity (SFBC+FSTD)scheme as still another embodiment according to the principles of thepresent invention;

FIG. 9 schematically illustrates a transmission structure of the primarybroadcast channel (PBCH);

FIG. 10 schematically illustrates a Space Frequency Block Code combinedwith Frequency Switched Transmit Diversity (SFBC+FSTD) scheme as yetanother embodiment according to the principles of the present invention;

FIG. 11 schematically illustrates a Space Frequency Block Code combinedwith Frequency Switched Transmit Diversity (SFBC+FSTD) scheme as stillanother embodiment according to the principles of the present invention;

FIG. 12 schematically illustrates procedures for PBCH burst timingrecovery according to one embodiment of the principles of the presentinvention; and

FIG. 13 schematically illustrates a Space Frequency Block Code combinedwith Frequency Switched Transmit Diversity (SFBC+FSTD) scheme as afurther embodiment according to the principles of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. As those skilled in the art would realize,the described embodiments may be modified in various different ways, allwithout departing from the spirit or scope of the present invention.

FIG. 1 illustrates an Orthogonal Frequency Division Multiplexing (OFDM)transceiver chain. In a communication system using OFDM technology, attransmitter chain 110, control signals or data 111 is modulated bymodulator 112 and is serial-to-parallel converted by Serial/Parallel(S/P) converter 113. Inverse Fast Fourier Transform (IFFT) unit 114 isused to transfer the signal from frequency domain to time domain. Cyclicprefix (CP) or zero prefix (ZP) is added to each OFDM symbol by CPinsertion unit 116 to avoid or mitigate the impact due to multipathfading. Consequently, the signal is transmitted by transmitter (Tx)front end processing unit 117, such as an antenna (not shown), oralternatively, by fixed wire or cable. At receiver chain 120, assumingperfect time and frequency synchronization are achieved, the signalreceived by receiver (Rx) front end processing unit 121 is processed byCP removal unit 122. Fast Fourier Transform (FFT) unit 124 transfers thereceived signal from time domain to frequency domain for furtherprocessing.

The total bandwidth in an OFDM system is divided into narrowbandfrequency units called subcarriers. The number of subcarriers is equalto the FFT/IFFT size N used in the system. In general, the number ofsubcarriers used for data is less than N because some subcarriers at theedge of the frequency spectrum are reserved as guard subcarriers. Ingeneral, no information is transmitted on guard subcarriers.

The scheme of diversity is widely used to combat the effect of fastfading by providing a receiver with multiple faded replicas of the sameinformation-bearing signal. An example of open-loop transmissiondiversity scheme is the Alamouti 2×1 space-time block code (STBC)transmission diversity scheme as illustrated in FIG. 2. In thisapproach, during any symbol period, i.e., time period, a transmittertransmits two data symbols via two transmission antennas to a receiver.As shown in FIG. 2, during the first symbol interval t1, symbols S₁ andS₂ are respectively transmitted via antennas ANT 1 and ANT 2. During thenext symbol period t2, symbols −S*₂ and S*₁ are respectively transmittedvia antennas ANT 1 and ANT 2, where x* represents complex conjugate ofx. After receiving the signals, the receiver performs a plurality ofprocesses to recover original symbols S₁ and S₂. Note that theinstantaneous channel gains g1 and g2 for ANT 1 and ANT 2, respectively,are required for processing at the receiver. Therefore, the transmitterneeds to transmit separate pilot symbols via both the antennas ANT 1 andANT 2 for channel gain estimation at the receiver. The diversity gainachieved by Alamouti coding is the same as that achieved in MaximumRatio Combining (MRC).

The 2×1 Alamouti scheme can also be implemented in a space-frequencyblock code (SFBC) transmission diversity scheme as illustrated in FIG.3. As shown in FIG. 3, symbols S₁ and S₂ are respectively transmitted toa receiver via antennas ANT 1 and ANT 2 on a first subcarrier havingfrequency f1 in an Orthogonal Frequency Division Multiplexing (OFDM)system, symbols −S*₂ and S*₁ are respectively transmitted via antennasANT 1 and ANT 2 on a second subcarrier having frequency f2. Therefore amatrix of transmitted symbols from antennas ANT 1 and ANT 2 can bewritten as:

$\begin{matrix}{{\begin{bmatrix}T_{11} & T_{12} \\T_{21} & T_{22}\end{bmatrix} = \begin{bmatrix}S_{1} & {- S_{2}^{*}} \\S_{2} & S_{1}^{*}\end{bmatrix}},} & (1)\end{matrix}$The received signal at the receiver on subcarrier having frequency f1 isr₁, and the received signal at the receiver on subcarrier havingfrequency f2 is r₂. r₁ and r₂ can be written as:r ₁ =h ₁ s ₁ +h ₂ s ₂ +n ₁r ₂ =−h ₁ s ₂ *+h ₂ s ₁ *+n ₂  (2)where h₁ and h₂ are channel gains from ANT 1 and ANT 2 respectively. Wealso assume that the channel from a given antennas does not changebetween subcarrier having frequency f₁ and subcarrier having frequencyf₂. The receiver performs equalization on the received signals andcombines the two received signals (r₁ and r₂) to recover the symbols S₁and S₂. The recovered symbols Ŝ₁ and Ŝ₂ can be written as:ŝ ₁ =h* ₁ r ₁ +h ₂ r* ₂=h* ₁(h ₁ s ₁ +h ₂ s ₂ +n ₁)+h ₂(−h ₁ s* ₂ +h ₂ s* ₁ +n ₂)*=(|h ₁|² +|h ₂|²)s ₁ +h* ₁ n ₁ +h ₂ n* ₂ŝ ₂ =h* ₂ r ₁ +h ₁ r* ₂=h* ₂(h ₁ s ₁ +h ₂ s ₂ +n ₁)+h ₁(−h ₁ s* ₂ +h ₂ s* ₁ +n ₂)*=(|h ₁|² +|h ₂|²)s ₂ +h* ₂ n ₁ +h ₁ n* ₂  (3)It can be seen that both of the transmitted symbols Ŝ₁ and Ŝ₂ achievefull spatial diversity, that is, the each of the transmitted symbols Ŝ₁and Ŝ₂ completely removes an interference from the other one.

An alternative mapping for two transmission antennas SFBC scheme isshown in FIG. 4. A matrix of transmitted symbols from antennas ANT 1 andANT 2 can be written as:

$\begin{matrix}{{\begin{bmatrix}T_{11} & T_{12} \\T_{21} & T_{22}\end{bmatrix} = \begin{bmatrix}S_{1} & S_{2} \\{- S_{2}^{*}} & S_{1}^{*}\end{bmatrix}},} & (4)\end{matrix}$The transmit matrix in Equation (7) for the scheme in FIG. 4 is atranspose of the transmit matrix in Equation (4) for the scheme shown inFIG. 3.

Other proposals found in the art for four transmission antennas transmitdiversity combines Frequency Switched Transmit Diversity (FSTD) or TimeSwitched Transmit Diversity (TSTD) with block codes. In case of combinedSFBC+FSTD scheme or STBC+TSTD scheme, the matrix of the transmittedsymbols from the four transmission antennas are given as:

$\begin{matrix}{\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = {\begin{bmatrix}S_{1} & S_{2} & 0 & 0 \\{- S_{2}^{*}} & S_{1}^{*} & 0 & 0 \\0 & 0 & S_{3} & S_{4} \\0 & 0 & {- S_{4}^{*}} & S_{3}^{*}\end{bmatrix}.}} & (5)\end{matrix}$where T_(ij) represents symbol transmitted on the ith antenna and thejth subcarrier or jth time slot, and i=1, 2, 3, 4, j=1, 2, 3, 4 for thecase of four transmission antennas. A and B are block codes given asbelow.

$\begin{matrix}{{A = {\frac{1}{\sqrt{2}}\begin{bmatrix}S_{1} & S_{2} \\{- S_{2}^{*}} & S_{1}^{*}\end{bmatrix}}}{B = {\frac{1}{\sqrt{2}}\begin{bmatrix}S_{3} & S_{4} \\{- S_{4}^{*}} & S_{3}^{*}\end{bmatrix}}}} & (6)\end{matrix}$

The problem with combined SFBC+FSTD scheme and STBC+TSTD schemes is thatonly a fraction of the total transmission antennas and hence poweramplifier (PA) capability is used for transmission in a given frequencyor time resource. This is indicated by ‘0’ elements in the SFBC+FSTD andSTBC+TSTD matrix given above. When the transmit power on the non-zeroelements in the matrix is increased, bursty interference is generated tothe neighboring cells degrading system performance.

In a previous U.S. patent application titled “Transmit Diversity in aWireless communication System”, filed on 27 Dec. 2007, U.S. patentapplication Ser. No. 12/005,341, an open-loop transmit diversity schemewhere Alamouti block code is spread with an orthogonal function toprovide diversity for cases of more than two transmission antennas isproposed. An example of orthogonal functions uses columns of a Fouriermatrix.

A Fourier matrix is a N×N square matrix with entries given by:P _(N) =e ^(j2πmn/N) m,n=0,1, . . . (N−1)  (7)For example, a 2×2 Fourier matrix can be expressed as:

$\begin{matrix}{P_{2} = {\begin{bmatrix}1 & 1 \\1 & {\mathbb{e}}^{j\pi}\end{bmatrix} = {\begin{bmatrix}1 & 1 \\1 & {- 1}\end{bmatrix}.}}} & (8)\end{matrix}$Similarly, a 4×4 Fourier matrix can be expressed as:

$\begin{matrix}{P_{4} = {\begin{bmatrix}1 & 1 & 1 & 1 \\1 & {\mathbb{e}}^{{j\pi}/2} & {\mathbb{e}}^{j\pi} & {\mathbb{e}}^{j\; 3{\pi/2}} \\1 & {\mathbb{e}}^{j\pi} & {\mathbb{e}}^{j2\pi} & {\mathbb{e}}^{j\; 3\pi} \\1 & {\mathbb{e}}^{j\; 3{\pi/2}} & {\mathbb{e}}^{j\; 3\pi} & {\mathbb{e}}^{j\; 9{\pi/2}}\end{bmatrix} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & j & {- 1} & {- j} \\1 & {- 1} & 1 & {- 1} \\1 & {- j} & {- 1} & j\end{bmatrix}}} & (9)\end{matrix}$Multiple Fourier matrices can be defined by introducing a shiftparameter (g/G) in the Fourier matrix. The entry of the multiple Fouriermatrices is given by:

$\begin{matrix}{{P_{mn} = {{\mathbb{e}}^{j\; 2\pi{\frac{m}{N} \cdot {({n + \frac{g}{G}})}}}\mspace{14mu} m}},{n = 0},1,{\ldots\mspace{11mu}\left( {N - 1} \right)}} & (10)\end{matrix}$A set of four 2×2 Fourier matrices can be defined by taking G=4, andg=0, 1, 2 and 3 are written as:

$\begin{matrix}{{P_{2}^{0} = \begin{bmatrix}1 & 1 \\1 & {- 1}\end{bmatrix}},{P_{2}^{1} = \begin{bmatrix}1 & 1 \\{\mathbb{e}}^{j\;{\pi/4}} & {- {\mathbb{e}}^{j\;{\pi/4}}}\end{bmatrix}},{P_{2}^{2} = \begin{bmatrix}1 & 1 \\{\mathbb{e}}^{j\;{\pi/2}} & {- {\mathbb{e}}^{j\;{\pi/2}}}\end{bmatrix}},{P_{2}^{3} = {\begin{bmatrix}1 & 1 \\{\mathbb{e}}^{j\; 3{\pi/4}} & {- {\mathbb{e}}^{j\; 3{\pi/4}}}\end{bmatrix}.}}} & (11)\end{matrix}$Note that in addition to the set of four Fourier matrices listed above,we can also apply row or column permuted versions of these set ofFourier matrices. For example, the row and column permutations of thematrix P₂ ⁰ is given by:

$\begin{matrix}{{P_{2}^{5} = {\frac{1}{\sqrt{2}}\begin{bmatrix}1 & 1 \\{- 1} & 1\end{bmatrix}}},{P_{2}^{6} = {\frac{1}{\sqrt{2}}\begin{bmatrix}1 & {- 1} \\1 & 1\end{bmatrix}}}} & (12)\end{matrix}$For each Fourier matrix, there are two permuted versions. So the totalnumber of the spread matrix P is 12.

We assume that four symbols S₁, S₂, S₃ and S₄ are transmitted on foursubcarriers using four transmit antennas. Let us define matrix A and Bas below:

$\quad\begin{matrix}{{A = {\frac{1}{\sqrt{2}}\begin{bmatrix}S_{1} & {- S_{2}^{*}} \\S_{2} & S_{1}^{*}\end{bmatrix}}}{B = {\frac{1}{\sqrt{2}}\begin{bmatrix}S_{3} & {- S_{4}^{*}} \\S_{4} & S_{3}^{*}\end{bmatrix}}}} & (13)\end{matrix}$It can be seen that each matrix A and B is an Alamouti code for symbols(S₁, S₂) and symbols (S₃, S₄) respectively. We construct a 2×2 matrixwith A and B as its elements and perform an element-by-elementmultiplication with an expanded 2×2 Fourier matrix as below.

$\begin{matrix}{{T_{i} = {{{\frac{1}{\sqrt{2}}\begin{bmatrix}A & A \\B & B\end{bmatrix}}.}*\left( {P_{2}^{i} \otimes \begin{bmatrix}1 & 1 \\1 & 1\end{bmatrix}} \right)}},\mspace{14mu}{{{for}\mspace{14mu} i} = 1},...\mspace{14mu},12.} & (14)\end{matrix}$Note that the operator .* denotes element-wise multiplication and{circle around (×)} denotes kronecker product. For i=0 case, theresulting 4×4 matrix denoting discrete Fourier transform (DFT)-spreadSFBC or DFT-spread STBC is given as below:

$\quad\begin{matrix}{T_{0} = {{{{\frac{1}{\sqrt{2}}\begin{bmatrix}A & A \\B & B\end{bmatrix}}.}*\left( {P_{2}^{0} \otimes \begin{bmatrix}1 & 1 \\1 & 1\end{bmatrix}} \right)}\mspace{25mu} = {{{{\frac{1}{\sqrt{2}}\begin{bmatrix}A & A \\B & B\end{bmatrix}}.}*\left( {{\frac{1}{\sqrt{2}}\begin{bmatrix}1 & 1 \\1 & {- 1}\end{bmatrix}} \otimes \begin{bmatrix}1 & 1 \\1 & 1\end{bmatrix}} \right)}\mspace{25mu} = {\frac{1}{\sqrt{4}}\begin{bmatrix}S_{1} & S_{2} & S_{1} & S_{2} \\{- S_{2}^{*}} & S_{1}^{*} & {- S_{2}^{*}} & S_{1}^{*} \\S_{3} & S_{4} & {- S_{3}} & {- S_{4}} \\{- S_{4}^{*}} & S_{3}^{*} & S_{4}^{*} & {- S_{3}^{*}}\end{bmatrix}}}}} & (15)\end{matrix}$It can be seen that in this scheme transmission takes placesimultaneously from all the transmit antennas and all the subcarriers.This spreading of the transmitted symbols results in averaging of theinter-cell interference thuds improving system performance andthroughput.

The downlink reference signals mapping for four transmission antennas inthe 3GPP LTE (3^(rd) Generation Partnership Project Long Term Evolution)system is shown in FIG. 5. The notation R_(p) is used to denote aresource element used for reference signal transmission on antenna portp. It can be noted that density on antenna ports 2 and 3 is half thedensity on antenna ports 0 and 1. This leads to weaker channel estimateson antenna ports 2 and 3 relative to channel estimates on antenna ports0 and 1.

In the current invention we describe an open-loop transmission diversityscheme where Alamouti block code is spread with an orthogonal functionto provide diversity for transmissions via more than two transmissionantennas. We will describe the invention assuming a Fourier matrix. Itshould be noted that the principles of the current invention can beeasily extended and applied to the cases of other orthogonal functionssuch as Hadamard function or Zadoff-Chu (ZC) sequences.

In a previous U.S. patent application titled “Antenna Mapping in a MIMOWireless communication System”, filed on 11 Jan. 2008, U.S. patentapplication Ser. No. 12/007,586, an alternative mapping scheme forSFBC−FSTD scheme is proposed. In the proposed scheme, symbols (S₁, S₂)are transmitted over antennas ports 0 and 2, while symbols (S₃, S₄) aretransmitted over antenna ports 1 and 3 as given by the transmit matrixbelow:

$\begin{matrix}{{\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = \begin{bmatrix}S_{1} & {- S_{2}^{*}} & 0 & 0 \\0 & 0 & S_{3} & {- S_{4}^{*}} \\S_{2} & S_{1}^{*} & 0 & 0 \\0 & 0 & S_{4} & S_{3}^{*}\end{bmatrix}},} & (16)\end{matrix}$where T_(ij) represents symbol transmitted on the (i−1)th antenna portand the jth subcarrier or jth time slot (i=1, 2, 3, 4, j=1, 2, 3, 4) forthe case of 4-Tx antennas. It can be noted that this mapping result inaveraging of the unequal channel estimation error effect across thetransmitted symbols.

In a first embodiment according to the principles of the presentinvention, we propose a SFBC−FSTD scheme where mapping of symbols toantennas is changed on repeated symbols as shown in FIG. 6. In thisexample we assumed that four symbols S₁, S₂, S₃ and S₄ are transmittedwith one repetition over eight subcarriers. In the first foursubcarriers, symbols S₁ and S₂ are transmitted on antennas ports ANT0and ANT1, while symbols S₃ and S₄ are transmitted on antennas ports ANT2and ANT3. On repetition in the next four subcarriers, the symbols S₁ andS₂ are transmitted on antennas ports ANT2 and ANT3, while symbols S₃ andS₄ are transmitted on antennas ports ANT0 and ANT1. This proposedmapping results in greater diversity gain compared to the transmissionwhere mapping does not change on repetition. This diversity gains stemsfrom the fact that after one repetition all the four symbols aretransmitted from all the four transmit antennas.

In the proposed mapping scheme in the first embodiment of the presentinvention, the transmission matrix T₁ shown below is used for initialtransmission:

$\begin{matrix}{T_{1} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = \begin{bmatrix}S_{1} & S_{2} & 0 & 0 \\{- S_{2}^{*}} & S_{1}^{*} & 0 & 0 \\0 & 0 & S_{3} & S_{4} \\0 & 0 & {- S_{4}^{*}} & S_{3}^{*}\end{bmatrix}}} & (17)\end{matrix}$where T_(ij) represents symbol transmitted on the ith antenna and thejth subcarrier or jth time slot (i=1, 2, 3, 4, j=1, 2, 3, 4) for thecase of 4-Tx antennas. When the same symbols are repeated, a differentmapping matrix T₂ shown below is used for transmission:

$\begin{matrix}{T_{2} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = \begin{bmatrix}S_{3} & S_{4} & 0 & 0 \\{- S_{4}^{*}} & S_{3}^{*} & 0 & 0 \\0 & 0 & S_{1} & S_{2} \\0 & 0 & {- S_{2}^{*}} & S_{1}^{*}\end{bmatrix}}} & (18)\end{matrix}$

In a second embodiment according to the principles of the presentinvention as shown in FIG. 7, the transmitted symbols S₁, S₂, S₃ and S₄are repeated three times. In this case, the transmission matrix T₁ isused for first transmission and second repetition, while thetransmission matrix T₂ is used for first and third repetitions.

In a third embodiment according to the principles of the presentinvention as shown in FIG. 8, the transmitted symbols S₁, S₂, S₃ and S₄are repeated N>2 times, where the N−1 repetitions are ‘full repetition’and the last one is partial repetition in that only part of the symbolsS1, S2, S3 and S4 are repeated. As shown in FIG. 8, the first and secondrepetitions are full repetitions while the third repetition is a partialrepetition. The two transmission matrices T1 and T2 are applied to theseN repetitions in an alternating fashion, such that the first repetitionuses T1, second repetition uses T2, etc.

In a fourth embodiment according to the principles of the presentinvention, the transmitted symbols S₁, S₂, S₃ and S₄ in FIG. 6 and FIG.7, as well as their repetitions, belong to one burst of the primarybroadcast channel (P-BCH, also known as common control physical channel(CCPCH)). The transmission structure of the P-BCH channel is illustratedin FIG. 8, for an example where two bursts spaced 20 ms apart aretransmitted in a 40 ms interval. Within each burst, there are severalrepetitions of the interleaved codeword C. All repetitions of thesecodewords are QPSK modulated. That is, the information to be transmittedis first encoded and then interleaved. An interleaver can be as simpleas writing data in rows and reading out data in columns. An interleavedcodeword is the coded and interleaved information. With QPSK modulation,each pair of coded bits is mapped to a QPSK symbol. As shown in FIG. 6and FIG. 7, repetitions of the modulated codeword is assigned differentSFBC−FSTD schemes as the modulated symbols are mapped to physicalresource elements.

In a fifth embodiment according to the principles of the presentinvention as shown in FIG. 9, the transmitted symbols S₁, S₂, S₃ and S₄are repeated once. The four symbols are transmitted over foursubcarriers and two timeslots. In this case, transmission matrix T₁ isused for first transmission in the first timeslot while transmissionmatrix T₂ is used for first repetition in the second timeslot.

In a sixth embodiment according to the principles of the presentinvention, the total number of time slots FIG. 9 are four, includingfirst transmission, second transmission, third transmission and fourthtransmission, and these transmissions are separated in time. That is,these transmissions are separated from each other by a certain timeinterval, during which none of the first transmission, secondtransmission, third transmission or fourth transmission occurs.

In a seventh embodiment according to the principles of the presentinvention, the transmitted symbols in both the first timeslot and secondtimeslot in FIG. 9 belong to the first burst of the PBCH transmissionshown in FIG. 8. In this case, these two timeslots locates in the same 1ms subframe.

In an eighth embodiment according to the principles of the presentinvention, the transmitted symbols in the first timeslot in FIG. 9belong to the first burst of the PBCH transmission shown in FIG. 8.Meanwhile, the transmitted symbols in the second timeslot in FIG. 9belong to the second burst of the PBCH transmission shown in FIG. 8.

In a ninth embodiment according to the principles of the presentinvention as shown in FIG. 10, the transmitted symbols S₁, S₂, S₃ and S₄are repeated three times with a total number of transmissions of four.The four symbols are transmitted over eight subcarriers and twotimeslots. In this case, the transmission matrix T₁ is used for thefirst transmission and first repetition (i.e., the second transmission)in the first timeslot, while the transmission matrix T₂ is used for thesecond repetition (i.e., the third transmission) and the thirdrepetition (i.e., the fourth transmission) in the second timeslot.

In a tenth embodiment according to the principles of the presentinvention, the total number of time slots are four, including firsttransmission, second transmission, third transmission and fourthtransmission, and these transmissions are separated in time. That is,the four symbols S₁, S₂, S₃ and S₄ are repeatedly transmitted for fourtimes over eight subcarriers and four timeslots, such that: the foursymbols are first transmitted over subcarriers f1˜f4 in Timeslot #1 (thefirst transmission); the four symbols are secondly transmitted oversubcarriers f5˜f8 in Timeslot #2 (the second transmission); the foursymbols are thirdly transmitted over subcarriers f1˜f4 in Timeslot #3(the third transmission); and the four symbols are fourthly transmittedover subcarriers f5˜f8 in Timeslot #4 (the fourth transmission). Notethat this embodiment can be extended by a transmission of four symbolsover sixteen subcarriers in two time slots. In this case, the totalnumber of transmissions is eight, since four subcarriers in one timeslot are used for one transmission.

In an eleventh embodiment according to the principles of the presentinvention, the transmitted symbols in both the first timeslot and secondtimeslot in FIG. 10 belong to the first burst of the PBCH transmissionshown in FIG. 8. In this case, these two timeslots live in the same 1 mssubframe.

In a twelfth embodiment according to the principles of the presentinvention, the transmitted symbols in the first timeslot in FIG. 10belong to the first burst of the PBCH transmission shown in FIG. 8;meanwhile, the transmitted symbols in the second timeslot in FIG. 10belong to the second burst of the PBCH transmission shown in FIG. 8.

An example of six symbols transmitted over six antennas in sixsubcarriers is given below. Three transmission matrices T₁, T₂, T₃ canbe respectively established as:

$\begin{matrix}{{T_{1} = \begin{bmatrix}S_{1} & {- S_{2}^{*}} & 0 & 0 & 0 & 0 \\S_{2} & S_{1}^{*} & 0 & 0 & 0 & 0 \\0 & 0 & S_{3} & {- S_{4}^{*}} & 0 & 0 \\0 & 0 & S_{4} & S_{3}^{*} & 0 & 0 \\0 & 0 & 0 & 0 & S_{5} & {- S_{6}^{*}} \\0 & 0 & 0 & 0 & S_{6} & S_{5}^{*}\end{bmatrix}},} & (19) \\{{T_{2} = \begin{bmatrix}S_{5} & {- S_{6}^{*}} & 0 & 0 & 0 & 0 \\S_{6} & S_{5}^{*} & 0 & 0 & 0 & 0 \\0 & 0 & S_{1} & {- S_{2}^{*}} & 0 & 0 \\0 & 0 & S_{2} & S_{1}^{*} & 0 & 0 \\0 & 0 & 0 & 0 & S_{3} & {- S_{4}^{*}} \\0 & 0 & 0 & 0 & S_{4} & S_{3}^{*}\end{bmatrix}},} & (20) \\{T_{3} = {\begin{bmatrix}S_{3} & {- S_{4}^{*}} & 0 & 0 & 0 & 0 \\S_{4} & S_{3}^{*} & 0 & 0 & 0 & 0 \\0 & 0 & S_{5} & {- S_{6}^{*}} & 0 & 0 \\0 & 0 & S_{6} & S_{5}^{*} & 0 & 0 \\0 & 0 & 0 & 0 & S_{1} & {- S_{2}^{*}} \\0 & 0 & 0 & 0 & S_{2} & S_{1}^{*}\end{bmatrix}.}} & (21)\end{matrix}$The three transmission matrices T₁, T₂, T₃ can be used on the first,second and third transmission, respectively. In this way, eachmodulation symbols is transmitted over all of the six antennas and thuscapturing six-antenna transmit diversity.

In a thirteenth embodiment according to the principles of the presentinvention, when there are only two PBCH bursts that are spaced 20 msapart, and these two PBCH bursts are carried using different SFBC+FSTDformats as shown in FIG. 10 and FIG. 11, the PBCH burst timing (thetransmission frame timing) can be obtained by hypothesis testing againstthese two different SFBC+FSTD formats. For example, if matrix T₁ is usedin the first 5 msec of a 10 msec frame, and matrix T₂ is used in thesecond 5 msec of the 10 msec frame. Then, on successful decoding, thereceiver can determine where the 10 msec frame boundary starts. Thereceiver flowchart for timing identification is shown in FIG. 12. First,a unit of user equipment (UE) receives the PBCH signal at the currentradio frame from a base station (BS) (step 210). The current radio framecontains the two PBCH bursts that are spaces 20 ms apart. The UEattempts to decode the PBCH signal at the current frame by assuming theSFBC format of time slot #1 as shown in FIG. 10 or FIG. 11 (step 220).Then, the UE determines whether the PBCH signal is successfully decoded(step 230). When the PBCH signal is successfully decoded, the UE stopsthe decoding procedure (step 240). Otherwise, the UE soft combines thecurrent burst and the previous burst, and attempts to decode thecombined signal by assuming SFBC format of time slot #2 for the currentburst, and assuming the SFBC format of time slot 1 for the previousburst (step 250). Soft combining means that the UE combines themodulation symbols and hence the energy received in the two time slots.Then, the UE determines whether the PBCH signal is successfully decoded(step 260). When the PBCH signal is successfully decoded, the UE stopsthe decoding procedure (step 270). Otherwise, the UE buffers the currentburst, and moves on to the next radio frame (step 280).

In a fourteenth embodiment according to the principles of the presentinvention, the transmission matrices T₁ and T₂ are permuted:

$\begin{matrix}{T_{1} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = \begin{bmatrix}S_{1} & S_{2} & 0 & 0 \\0 & 0 & S_{3} & S_{4} \\{- S_{2}^{*}} & S_{1}^{*} & 0 & 0 \\0 & 0 & {- S_{4}^{*}} & S_{3}^{*}\end{bmatrix}}} & (22) \\{T_{2} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = \begin{bmatrix}S_{3} & S_{4} & 0 & 0 \\0 & 0 & S_{1} & S_{2} \\{- S_{4}^{*}} & S_{3}^{*} & 0 & 0 \\0 & 0 & {- S_{2}^{*}} & S_{1}^{*}\end{bmatrix}}} & (23)\end{matrix}$In these above permuted transmission matrices, in the transmissionmatrix T₁, symbols S₁ and S₂ are mapped to antenna ports ANT0 and ATN2while symbols S₃ and S₄ are mapped to antenna ports ANT1 and ANT3. Andin the transmission matrix T₂, symbols S₁ and S₂ are mapped to antennaports ANT1 and ANT3, while symbols S₃ and S₄ are mapped to antenna portsANT0 and ANT2. All the mapping schemes in FIGS. 6, 7, 10 and 11 aremodified accordingly to reflect the change in the transmission matrix.For example, FIG. 13 is a modification of FIG. 6 with the permutedtransmission matrix, where the transmitted symbols S₁, S₂, S₃ and S₄ arerepeated once with a total number of transmissions of two. The foursymbols are transmitted over eight subcarriers. In this case, symbol S₁and S₂ are mapped to antenna ports ANT0 and ATN2 while symbols S₃ and S₄are mapped to antenna ports ANT1 and ATN3. On repetition, symbol S₁ andS₂ are mapped to antenna ports ANT1 and ATN3 while symbols S₃ and S₄ aremapped to antenna ports ANT0 and ATN2.

In a fifteenth embodiment according to the principles of the presentinvention, the transmitted symbols S₁, S₂, S₃ and S₄ are repeatedaccording to FIG. 7, except that symbols S₁ and S₂ are mapped to antennaports ANT0 and ATN2 while symbols S₃ and S₄ are mapped to antenna portsANT1 and ANT3. On repetition, symbols S₁ and S₂ are mapped to antennaports ANT1 and ATN3 while symbols S₃ and S₄ are mapped to antenna portsANT0 and ANT2.

In a sixteenth embodiment according to the principles of the presentinvention, the transmission matrices T₁ and T₂ can be defined as below:

$\begin{matrix}{T_{1} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = {\frac{1}{\sqrt{4}}\begin{bmatrix}S_{1} & {- S_{2}^{*}} & S_{1} & {- S_{2}^{*}} \\S_{2} & S_{1}^{*} & S_{2} & S_{1}^{*} \\S_{3} & {- S_{4}^{*}} & {- S_{3}} & S_{4}^{*} \\S_{4} & S_{3}^{*} & {- S_{4}} & {- S_{3}^{*}}\end{bmatrix}}}} & (24) \\{T_{2} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = {\frac{1}{\sqrt{4}}\begin{bmatrix}S_{1} & {- S_{2}^{*}} & S_{1} & {- S_{2}^{*}} \\S_{3} & {- S_{4}^{*}} & {- S_{3}} & S_{4}^{*} \\S_{2} & S_{1}^{*} & S_{2} & S_{1}^{*} \\S_{4} & S_{3}^{*} & {- S_{4}} & {- S_{3}^{*}}\end{bmatrix}}}} & (25)\end{matrix}$The matrix T₂ is obtained by inter-changing the second and third rows inT₁.

While the above embodiment of the present invention has been shown totransmit four data symbols S₁, S₂, S₃ and S₄, the present invention isnot limited to the transmission of four data symbols. That is, any mountof data can be transmitted by applying the above proposed transmissionschemes. The total symbols need to be divided into groups of foursymbols and then the proposed transmission schemes can be applied toeach of the four symbols. Note that in an OFDM system, there are a largenumber of subcarriers, such as 600 subcarriers in a LTE 10 MHz system.Therefore, each group of four symbols can be repeated a few times.Moreover, there are multiple OFDM symbols within a subframe and eachOFDM symbol contains 600 subcarriers in the above example. Therefore,the total number of symbols that can be transmitted over 600 subcarrierscan be large.

Moreover, the present invention can be applied to transmissions overmore than four antennas, such as eight antennas. In addition, thetransmission scheme can be applied at both a base station (BS) and auser equipment (UE).

While the present invention has been shown and described in connectionwith the preferred embodiments, it will be apparent to those skilled inthe art that modifications and variations can be made without departingfrom the spirit and scope of the invention as defined by the appendedclaims.

1. A method for transmission in a communication system, the methodcomprising: modulating data to be transmitted by using a certainmodulation scheme to generate a plurality of modulated symbols;establishing a transmit diversity scheme for at least a group of foursymbols S₁, S₂, S₃ and S₄ from among the plurality of modulated symbols,with the transmit diversity scheme being established such that twotransmission matrices T₁ and T₂ are alternatively applied in a frequencydomain, and the two transmission matrices T₁ and T₂ being respectivelyestablished by: ${T_{1} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = \begin{bmatrix}S_{1} & S_{2} & 0 & 0 \\{- S_{2}^{*}} & S_{1}^{*} & 0 & 0 \\0 & 0 & S_{3} & S_{4} \\0 & 0 & {- S_{4}^{*}} & S_{3}^{*}\end{bmatrix}}},{and}$ ${T_{2} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = \begin{bmatrix}S_{3} & S_{4} & 0 & 0 \\{- S_{4}^{*}} & S_{3}^{*} & 0 & 0 \\0 & 0 & S_{1} & S_{2} \\0 & 0 & {- S_{2}^{*}} & S_{1}^{*}\end{bmatrix}}},$ where T_(ij) represents the symbol to be transmittedon the ith antenna and the jth subcarrier; and transmitting the foursymbols S₁, S₂, S₃ and S₄ via four antennas in accordance with thetransmit diversity scheme.
 2. The method of claim 1, further comprisingexchanging the second row and the third row of each of the transmissionmatrices T₁ and T₂, such that the symbols on the second row of each ofthe transmission matrices T₁ and T₂ are transmitted via the thirdantenna, and the symbols on the third row of each of the transmissionmatrices are transmitted via the second antenna.
 3. The method of claim1, comprised of the transmit diversity scheme being established suchthat the four symbols are repeatedly transmitted in the frequency domainfor two times, with: one of the two transmission matrices T₁ and T₂being applied to the first transmission; and the other one of the twotransmission matrices T₁ and T₂ being applied to the secondtransmission.
 4. The method of claim 3, further comprising exchangingthe second row and the third row of each of the transmission matrices T₁and T₂, such that the symbols on the second row of each of thetransmission matrices T₁ and T₂ are transmitted via the third antenna,and the symbols on the third row of each of the transmission matricesare transmitted via the second antenna.
 5. The method of claim 1,comprised of the transmit diversity scheme being established such thatthe four symbols are repeatedly transmitted in the frequency domain forN times, with N being a positive number and N>1, with: one of the twotransmission matrices T₁ and T₂ being applied to odd numberedtransmissions; and the other one of the two transmission matrices T₁ andT₂ being applied to even numbered transmissions.
 6. The method of claim5, comprised of: the first through (N−1)-th transmissions being fullrepetitions; and the N-th transmission being a partial repetition. 7.The method of claim 5, further comprising exchanging the second row andthe third row of each of the transmission matrices T₁ and T₂, such thatthe symbols on the second row of each of the transmission matrices T₁and T₂ are transmitted via the third antenna, and the symbols on thethird row of each of the transmission matrices are transmitted via thesecond antenna.
 8. The method of claim 1, comprised of transmitting thefour symbols as a burst of signal in a primary broadcast channel, withthe transmission being in accordance with the transmit diversity scheme.9. The method of claim 8, comprised of transmitting two bursts in acertain time interval, with the transmission of each burst being inaccordance with the transmit diversity scheme.
 10. A method fortransmission in a communication system, the method comprising the stepsof: calculating cyclic redundancy checks for a plurality of informationbits to be transmitted; appending the calculated cyclic redundancychecks to the plurality of information bits to generate a transportblock; convolving the transport block by applying a convolution code tothe transport block to generate a convolved transport block;interleaving the convolved transport block to generated an interleavedcodeword; repeating the interleaved codeword for several times;modulating the repeated interleaved codewords by using a certainmodulation scheme to generate a plurality of modulated symbols;establishing a transmit diversity scheme for at least a group of foursymbols S₁, S₂, S₃ and S₄ from among the plurality of modulated symbols,with the transmit diversity scheme being established such that twotransmission matrices T₁ and T₂ are alternatively applied in a frequencydomain, and the two transmission matrices T₁ and T₂ being respectivelyestablished by: ${T_{1} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = \begin{bmatrix}S_{1} & S_{2} & 0 & 0 \\{- S_{2}^{*}} & S_{1}^{*} & 0 & 0 \\0 & 0 & S_{3} & S_{4} \\0 & 0 & {- S_{4}^{*}} & S_{3}^{*}\end{bmatrix}}},{and}$ ${T_{2} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = \begin{bmatrix}S_{3} & S_{4} & 0 & 0 \\{- S_{4}^{*}} & S_{3}^{*} & 0 & 0 \\0 & 0 & S_{1} & S_{2} \\0 & 0 & {- S_{2}^{*}} & S_{1}^{*}\end{bmatrix}}},$ where T_(ij) represents the symbol to be transmittedon the ith antenna and the jth subcarrier; and transmitting the foursymbols S₁, S₂, S₃ and S₄ via four antennas as a burst of signal in aprimary broadcast channel, with the transmission being in accordancewith the transmit diversity scheme.
 11. The method of claim 10, furthercomprising transmitting two bursts in a certain time interval, with thetransmission of each burst being in accordance with the transmitdiversity scheme.
 12. A method for transmission in a communicationsystem, the method comprising: modulating data to be transmitted byusing a certain modulation scheme to generate a plurality of modulatedsymbols; establishing a transmit diversity scheme for at least a groupof four symbols S₁, S₂, S₃ and S₄ from among the plurality of modulatedsymbols, with the transmit diversity scheme being established such thattwo transmission matrices T₁ and T₂ are alternatively applied in a timedomain, and the two transmission matrices T₁ and T₂ being respectivelyestablished by: ${T_{1} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = \begin{bmatrix}S_{1} & S_{2} & 0 & 0 \\{- S_{2}^{*}} & S_{1}^{*} & 0 & 0 \\0 & 0 & S_{3} & S_{4} \\0 & 0 & {- S_{4}^{*}} & S_{3}^{*}\end{bmatrix}}},{and}$ ${T_{2} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = \begin{bmatrix}S_{3} & S_{4} & 0 & 0 \\{- S_{4}^{*}} & S_{3}^{*} & 0 & 0 \\0 & 0 & S_{1} & S_{2} \\0 & 0 & {- S_{2}^{*}} & S_{1}^{*}\end{bmatrix}}},$ where T_(ij) represents the symbol to be transmittedon the ith antenna and the jth subcarrier; and transmitting the foursymbols S₁, S₂, S₃ and S₄ via four antennas in accordance with thetransmit diversity scheme.
 13. The method of claim 12, furthercomprising exchanging the second row and the third row of each of thetransmission matrices T₁ and T₂, such that the symbols on the second rowof each of the transmission matrices T₁ and T₂ are transmitted via thethird antenna, and the symbols on the third row of each of thetransmission matrices are transmitted via the second antenna.
 14. Themethod of claim 12, comprised of the transmit diversity scheme beingestablished such that the four symbols are repeatedly transmitted in thetime domain for two times, with: one of the two transmission matrices T₁and T₂ being applied to the first transmission in a first time slot; andthe other one of the two transmission matrices T₁ and T₂ being appliedto the second transmission in a second time slot.
 15. The method ofclaim 14, comprised of transmitting the symbols in both of the both ofthe first time slot and the second time slot as one burst of signal in aprimary broadcast channel transmission, with the first time slot and thesecond time slot being located within the same subframe.
 16. The methodof claim 14, comprised of: transmitting the symbols in the first timeslot as a first burst of signal in a primary broadcast channeltransmission; and transmitting the symbols in the second time slot as asecond burst of signal in the primary broadcast channel transmission,with the first burst and the second burst being separated by a certaintime interval.
 17. The method of claim 14, further comprising exchangingthe second row and the third row of each of the transmission matrices T₁and T₂, such that the symbols on the second row of each of thetransmission matrices T₁ and T₂ are transmitted via the third antenna,and the symbols on the third row of each of the transmission matricesare transmitted via the second antenna.
 18. The method of claim 12,comprised of the transmit diversity scheme being established such thatthe four symbols are repeatedly transmitted in the time domain for aplurality of times, with: one of the two transmission matrices T₁ and T₂being applied to the odd numbered transmissions in odd numbered timeslots; and the other one of the two transmission matrices T₁ and T₂being applied to the even numbered transmissions in even numbered timeslots.
 19. The method of claim 18, further comprising exchanging thesecond row and the third row of each of the transmission matrices T₁ andT₂, such that the symbols on the second row of each of the transmissionmatrices T₁ and T₂ are transmitted via the third antenna, and thesymbols on the third row of each of the transmission matrices aretransmitted via the second antenna.
 20. A method for transmission in acommunication system, the method comprising: modulating data to betransmitted by using a certain modulation scheme to generate a pluralityof modulated symbols; establishing a transmit diversity scheme for atleast a group of four symbols S₁, S₂, S₃ and S₄ from among the pluralityof modulated symbols by alternatively applying two transmission matricesT₁ and T₂ in both of a time domain and a frequency domain, with the twotransmission matrices T₁ and T₂ being respectively established by:${T_{1} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = \begin{bmatrix}S_{1} & S_{2} & 0 & 0 \\{- S_{2}^{*}} & S_{1}^{*} & 0 & 0 \\0 & 0 & S_{3} & S_{4} \\0 & 0 & {- S_{4}^{*}} & S_{3}^{*}\end{bmatrix}}},{and}$ ${T_{2} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = \begin{bmatrix}S_{3} & S_{4} & 0 & 0 \\{- S_{4}^{*}} & S_{3}^{*} & 0 & 0 \\0 & 0 & S_{1} & S_{2} \\0 & 0 & {- S_{2}^{*}} & S_{1}^{*}\end{bmatrix}}},$ where T_(ij) represents the symbol to be transmittedon the ith antenna and the jth subcarrier; and transmitting the foursymbols S₁, S₂, S₃ and S₄ via four antennas in accordance with thetransmit diversity scheme.
 21. The method of claim 20, furthercomprising exchanging the second row and the third row of each of thetransmission matrices T₁ and T₂, such that the symbols on the second rowof each of the transmission matrices T₁ and T₂ are transmitted via thethird antenna, and the symbols on the third row of each of thetransmission matrices are transmitted via the second antenna.
 22. Themethod of claim 20, with the transmit diversity scheme being establishedsuch that the four symbols are repeatedly transmitted in the frequencydomain over eight subcarriers, and are repeatedly transmitted in thetime domain for two times over two time slots, with: in a first timeslot, a first one of the transmission matrix matrices T₁ and T₂ beingapplied to the first four subcarriers, and a second one of thetransmission matrix matrices T₁ and T₂ being applied to the last foursubcarriers; and in a second time slot, the second one of thetransmission matrix matrices T₁ and T₂ being applied to the first foursubcarriers, and the first one of the transmission matrix matrices T₁and T₂ being applied to the last four subcarriers.
 23. The method ofclaim 22, comprised of transmitting the symbols in the first and secondtime slots as one burst of signal in a primary broadcast channeltransmission, with the first time slot and the second time slot beinglocated within the same subframe.
 24. The method of claim 22, comprisedof: transmitting the symbols in the first time slot as a first burst ofsignal in a primary broadcast channel transmission; and transmitting thesymbols in the second time slot as a second burst of signal in theprimary broadcast channel transmission, with the first burst and thesecond burst being separated by a certain time interval.
 25. The methodof claim 22, further comprising exchanging the second row and the thirdrow of each of the transmission matrices T₁ and T₂, such that thesymbols on the second row of each of the transmission matrices T₁ and T₂are transmitted via the third antenna, and the symbols on the third rowof each of the transmission matrices are transmitted via the secondantenna.
 26. The method of claim 20, with the transmit diversity schemebeing established such that the four symbols are repeatedly transmittedfor four times over eight subcarriers four time slots, with: in a firsttime slot, a first one of the transmission matrix matrices T₁ and T₂being applied to the first four subcarriers; in a second time slot, asecond one of the transmission matrix matrices T₁ and T₂ being appliedto the last four subcarriers; in a third time slot, the first one of thetransmission matrix matrices T₁ and T₂ being applied to the first foursubcarriers; and in a fourth time slot, the second one of thetransmission matrix matrices T₁ and T₂ being applied to the last foursubcarriers.
 27. The method of claim 26, further comprising exchangingthe second row and the third row of each of the transmission matrices T₁and T₂, such that the symbols on the second row of each of thetransmission matrices T₁ and T₂ are transmitted via the third antenna,and the symbols on the third row of each of the transmission matricesare transmitted via the second antenna.
 28. A method for decoding signalin a communication system, the method comprising the steps of: receivinga first burst of signal and a second burst of signal within a radiosubframe; decoding the second burst of signal by applying a first spacefrequency block code format in which a transmission matrix T₁ isestablished by: ${T_{1} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = \begin{bmatrix}S_{1} & S_{2} & 0 & 0 \\{- S_{2}^{*}} & S_{1}^{*} & 0 & 0 \\0 & 0 & S_{3} & S_{4} \\0 & 0 & {- S_{4}^{*}} & S_{3}^{*}\end{bmatrix}}},$ where T_(ij) represents the symbol to be transmittedon the ith antenna and the jth subcarrier; determining whether thesecond burst of signal is successfully decoded; when the second burst ofsignal is not successfully decoded, softly combining the first burst ofsignal and the second burst of signal to generate a combined signal, anddecoding the combined signal by applying the first space frequency blockcode format to the first burst of signal, and applying a second spacefrequency block code format to the second burst of signal, with atransmission matrix T₂ within the second space frequency block codeformat being established by: ${T_{2} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = \begin{bmatrix}S_{3} & S_{4} & 0 & 0 \\{- S_{4}^{*}} & S_{3}^{*} & 0 & 0 \\0 & 0 & S_{1} & S_{2} \\0 & 0 & {- S_{2}^{*}} & S_{1}^{*}\end{bmatrix}}},$ where T_(ij) represents the symbol to be transmittedon the ith antenna and the jth subcarrier; determining whether thecombined signal is successfully decoded; and when the combined signal isnot successfully decoded, buffering the second burst of signal.
 29. Amethod for decoding signal in a communication system, the methodcomprising the steps of: receiving a first burst of signal and a secondburst of signal within a radio subframe; decoding the second burst ofsignal by applying a first space frequency block code format in which atransmission matrix T₁ and a transmission matrix T₂ are sequentiallyapplied in a frequency domain, with the transmission matrices T₁ and T₂being respectively established by: ${T_{1} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = \begin{bmatrix}S_{1} & S_{2} & 0 & 0 \\{- S_{2}^{*}} & S_{1}^{*} & 0 & 0 \\0 & 0 & S_{3} & S_{4} \\0 & 0 & {- S_{4}^{*}} & S_{3}^{*}\end{bmatrix}}},{T_{2} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = \begin{bmatrix}S_{3} & S_{4} & 0 & 0 \\{- S_{4}^{*}} & S_{3}^{*} & 0 & 0 \\0 & 0 & S_{1} & S_{2} \\0 & 0 & {- S_{2}^{*}} & S_{1}^{*}\end{bmatrix}}},$ where T_(ij) represents the symbol to be transmittedon the ith antenna and the jth subcarrier; determining whether thesecond burst of signal is successfully decoded; when the second burst ofsignal is not successfully decoded, softly combining the first burst ofsignal and the second burst of signal to generate a combined signal, anddecoding the combined signal by applying the first space frequency blockcode format to the first burst of signal, and applying a second spacefrequency block code format to the second burst of signal, with, in thesecond space frequency block code format, the transmission matrix T₂ andthe transmission matrix T₁ being sequentially applied in the frequencydomain; determining whether the combined signal is successfully decoded;and when the combined signal is not successfully decoded, buffering thesecond burst of signal.
 30. A method for transmission in a communicationsystem, the method comprising: modulating data to be transmitted byusing a certain modulation scheme to generate a plurality of modulatedsymbols; establishing a transmit diversity scheme for at least a groupof four symbols S₁, S₂, S₃ and S₄ from among the plurality of modulatedsymbols, with the transmit diversity scheme being established such thattwo transmission matrices T₁ and T₂ are alternatively applied in afrequency domain, and the two transmission matrices T₁ and T₂ beingrespectively established by: ${T_{1} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = {\frac{1}{\sqrt{4}}\begin{bmatrix}S_{1} & {- S_{2}^{*}} & S_{1} & {- S_{2}^{*}} \\S_{2} & S_{1}^{*} & S_{2} & S_{1}^{*} \\S_{3} & {- S_{4}^{*}} & {- S_{3}} & S_{4}^{*} \\S_{4} & S_{3}^{*} & {- S_{4}} & {- S_{3}^{*}}\end{bmatrix}}}},{and}$ ${T_{2} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = {\frac{1}{\sqrt{4}}\begin{bmatrix}S_{1} & {- S_{2}^{*}} & S_{1} & {- S_{2}^{*}} \\S_{3} & {- S_{4}^{*}} & {- S_{3}} & S_{4}^{*} \\S_{2} & S_{1}^{*} & S_{2} & S_{1}^{*} \\S_{4} & S_{3}^{*} & {- S_{4}} & {- S_{3}^{*}}\end{bmatrix}}}},$ where T_(ij) represents the symbol to be transmittedon the ith antenna and the jth subcarrier; and transmitting the foursymbols S₁, S₂, S₃ and S₄ via four antennas in accordance with thetransmit diversity scheme.
 31. A method for transmission in acommunication system, the method comprising: modulating data to betransmitted by using a certain modulation scheme to generate a pluralityof modulated symbols; establishing a transmit diversity scheme for atleast a group of four symbols S₁, S₂, S₃ and S₄ from among the pluralityof modulated symbols, with the transmit diversity scheme beingestablished such that two transmission matrices T₁ and T₂ arealternatively applied in a time domain, and the two transmissionmatrices T₁ and T₂ being respectively established by:${T_{1} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = {\frac{1}{\sqrt{4}}\begin{bmatrix}S_{1} & {- S_{2}^{*}} & S_{1} & {- S_{2}^{*}} \\S_{2} & S_{1}^{*} & S_{2} & S_{1}^{*} \\S_{3} & {- S_{4}^{*}} & {- S_{3}} & S_{4}^{*} \\S_{4} & S_{3}^{*} & {- S_{4}} & {- S_{3}^{*}}\end{bmatrix}}}},{and}$ ${T_{2} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = {\frac{1}{\sqrt{4}}\begin{bmatrix}S_{1} & {- S_{2}^{*}} & S_{1} & {- S_{2}^{*}} \\S_{3} & {- S_{4}^{*}} & {- S_{3}} & S_{4}^{*} \\S_{2} & S_{1}^{*} & S_{2} & S_{1}^{*} \\S_{4} & S_{3}^{*} & {- S_{4}} & {- S_{3}^{*}}\end{bmatrix}}}},$ where T_(ij) represents the symbol to be transmittedon the ith antenna and the jth subcarrier; and transmitting the foursymbols S₁, S₂, S₃ and S₄ via four antennas in accordance with thetransmit diversity scheme.
 32. A method for transmission in acommunication system, the method comprising: modulating data to betransmitted by using a certain modulation scheme to generate a pluralityof modulated symbols; establishing a transmit diversity scheme for atleast a group of four symbols S₁, S₂, S₃ and S₄ from among the pluralityof modulated symbols by alternatively applying two transmission matricesT₁ and T₂ in both of a time domain and a frequency domain, with the twotransmission matrices T₁ and T₂ being respectively established by:${T_{1} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = {\frac{1}{\sqrt{4}}\begin{bmatrix}S_{1} & {- S_{2}^{*}} & S_{1} & {- S_{2}^{*}} \\S_{2} & S_{1}^{*} & S_{2} & S_{1}^{*} \\S_{3} & {- S_{4}^{*}} & {- S_{3}} & S_{4}^{*} \\S_{4} & S_{3}^{*} & {- S_{4}} & {- S_{3}^{*}}\end{bmatrix}}}},{and}$ ${T_{2} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = {\frac{1}{\sqrt{4}}\begin{bmatrix}S_{1} & {- S_{2}^{*}} & S_{1} & {- S_{2}^{*}} \\S_{3} & {- S_{4}^{*}} & {- S_{3}} & S_{4}^{*} \\S_{2} & S_{1}^{*} & S_{2} & S_{1}^{*} \\S_{4} & S_{3}^{*} & {- S_{4}} & {- S_{3}^{*}}\end{bmatrix}}}},$ where T_(ij) represents the symbol to be transmittedon the ith antenna and the jth subcarrier; and transmitting the foursymbols S₁, S₂, S₃ and S₄ via four antennas in accordance with thetransmit diversity scheme.
 33. A wireless terminal in a communicationsystem, comprising: a modulation unit modulating data to be transmittedby using a certain modulation scheme to generate a plurality ofmodulated symbols; a processing unit establishing a transmit diversityscheme for at least a group of four symbols S₁, S₂, S₃ and S₄ from amongthe plurality of modulated symbols, with the transmit diversity schemebeing established such that two transmission matrices T₁ and T₂ arealternatively applied in a frequency domain, and the two transmissionmatrices T₁ and T₂ being respectively established by:${T_{1} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = \begin{bmatrix}S_{1} & S_{2} & 0 & 0 \\{- S_{2}^{*}} & S_{1}^{*} & 0 & 0 \\0 & 0 & S_{3} & S_{4} \\0 & 0 & {- S_{4}^{*}} & S_{3}^{*}\end{bmatrix}}},{and}$ ${T_{2} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = \begin{bmatrix}S_{3} & S_{4} & 0 & 0 \\{- S_{4}^{*}} & S_{3}^{*} & 0 & 0 \\0 & 0 & S_{1} & S_{2} \\0 & 0 & {- S_{2}^{*}} & S_{1}^{*}\end{bmatrix}}},$ where T_(ij) represents the symbol to be transmittedon the ith antenna and the jth subcarrier; and four antennastransmitting the four symbols S₁, S₂, S₃ and S₄ in accordance with thetransmit diversity scheme.
 34. The wireless terminal of claim 33,comprised of the processing unit exchanging the second row and the thirdrow of each of the transmission matrices T₁ and T₂, such that thesymbols on the second row of each of the transmission matrices T₁ and T₂are transmitted via the third antenna, and the symbols on the third rowof each of the transmission matrices are transmitted via the secondantenna.
 35. The wireless terminal of claim 33, comprised of thewireless terminal transmitting the four symbols as a burst of signal ina primary broadcast channel, with the transmission being in accordancewith the transmit diversity scheme.
 36. A wireless terminal in acommunication system, comprising: a modulation unit modulating data tobe transmitted by using a certain modulation scheme to generate aplurality of modulated symbols; a processing unit establishing atransmit diversity scheme for at least a group of four symbols S₁, S₂,S₃ and S₄ from among the plurality of modulated symbols, with thetransmit diversity scheme being established such that two transmissionmatrices T₁ and T₂ are alternatively applied in a time domain, and thetwo transmission matrices T₁ and T₂ being respectively established by:${T_{1} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = \begin{bmatrix}S_{1} & S_{2} & 0 & 0 \\{- S_{2}^{*}} & S_{1}^{*} & 0 & 0 \\0 & 0 & S_{3} & S_{4} \\0 & 0 & {- S_{4}^{*}} & S_{3}^{*}\end{bmatrix}}},{and}$ ${T_{2} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = \begin{bmatrix}S_{3} & S_{4} & 0 & 0 \\{- S_{4}^{*}} & S_{3}^{*} & 0 & 0 \\0 & 0 & S_{1} & S_{2} \\0 & 0 & {- S_{2}^{*}} & S_{1}^{*}\end{bmatrix}}},$ where T_(ij) represents the symbol to be transmittedon the ith antenna and the jth subcarrier; and four antennastransmitting the four symbols S₁, S₂, S₃ and S₄ in accordance with thetransmit diversity scheme.
 37. The wireless terminal of claim 36,comprised of the processing unit exchanging the second row and the thirdrow of each of the transmission matrices T₁ and T₂, such that thesymbols on the second row of each of the transmission matrices T₁ and T₂are transmitted via the third antenna, and the symbols on the third rowof each of the transmission matrices are transmitted via the secondantenna.
 38. The wireless terminal of claim 36, comprised of thetransmit diversity scheme being established such that the four symbolsare repeatedly transmitted in the time domain for two times, with: oneof the two transmission matrices T₁ and T₂ being applied to the firsttransmission in a first time slot; and the other one of the twotransmission matrices T₁ and T₂ being applied to the second transmissionin a second time slot.
 39. The wireless terminal of claim 38, comprisedof the wireless terminal transmitting the symbols in both of the firsttime slot and the second time slot as one burst of signal in a primarybroadcast channel transmission, with the first time slot and the secondtime slot being located within the same subframe.
 40. The wirelessterminal of claim 38, comprised of the wireless terminal: transmittingthe symbols in the first time slot as a first burst of signal in aprimary broadcast channel transmission; and transmitting the symbols inthe second time slot as a second burst of signal in the primarybroadcast channel transmission, with the first burst and the secondburst being separated by a certain time interval.
 41. A wirelessterminal in a communication system, comprising: a modulation unitmodulating data to be transmitted by using a certain modulation schemeto generate a plurality of modulated symbols; a processing unitestablishing a transmit diversity scheme for at least a group of foursymbols S₁, S₂, S₃ and S₄ from among the plurality of modulated symbolsby alternatively applying two transmission matrices T₁ and T₂ in both ofa time domain and a frequency domain, with the two transmission matricesT₁ and T₂ being respectively established by: ${T_{1} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = \begin{bmatrix}S_{1} & S_{2} & 0 & 0 \\{- S_{2}^{*}} & S_{1}^{*} & 0 & 0 \\0 & 0 & S_{3} & S_{4} \\0 & 0 & {- S_{4}^{*}} & S_{3}^{*}\end{bmatrix}}},{and}$ ${T_{2} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = \begin{bmatrix}S_{3} & S_{4} & 0 & 0 \\{- S_{4}^{*}} & S_{3}^{*} & 0 & 0 \\0 & 0 & S_{1} & S_{2} \\0 & 0 & {- S_{2}^{*}} & S_{1}^{*}\end{bmatrix}}},$ where T_(ij) represents the symbol to be transmittedon the ith antenna and the jth subcarrier; and four antennastransmitting the four symbols S₁, S₂, S₃ and S₄ in accordance with thetransmit diversity scheme.
 42. The wireless terminal of claim 41,comprised of the processing unit exchanging the second row and the thirdrow of each of the transmission matrices T₁ and T₂, such that thesymbols on the second row of each of the transmission matrices T₁ and T₂are transmitted via the third antenna, and the symbols on the third rowof each of the transmission matrices are transmitted via the secondantenna.
 43. The wireless terminal of claim 41, with the transmitdiversity scheme being established such that the four symbols arerepeatedly transmitted in the frequency domain over eight subcarriers,and are repeatedly transmitted in the time domain for two times over twotime slots, with: in a first time slot, a first one of the transmissionmatrix matrices T₁ and T₂ being applied to the first four subcarriers,and a second one of the transmission matrix matrices T₁ and T₂ beingapplied to the last four subcarriers; and in a second time slot, thesecond one of the transmission matrix matrices T₁ and T₂ being appliedto the first four subcarriers, and the first one of the transmissionmatrix matrices T₁ and T₂ being applied to the last four subcarriers.44. The wireless terminal of claim 41, with the transmit diversityscheme being established such that the four symbols are repeatedlytransmitted for four times over eight subcarriers four time slots, with:in a first time slot, a first one of the transmission matrix matrices T₁and T₂ being applied to the first four subcarriers; in a second timeslot, a second one of the transmission matrix matrices T₁ and T₂ beingapplied to the last four subcarriers; in a third time slot, the firstone of the transmission matrix matrices T₁ and T₂ being applied to thefirst four subcarriers; and in a fourth time slot, the second one of thetransmission matrix matrices T₁ and T₂ being applied to the last foursubcarriers.
 45. A wireless terminal a communication system, comprising:a memory unit storing a first burst of signal and a second burst ofsignal that are received within a radio subframe; and a decoding unitdecoding the received signals, with the decoding unit: decoding thesecond burst of signal by applying a first space frequency block codeformat in which a transmission matrix T₁ is established by:${T_{1} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = \begin{bmatrix}S_{1} & S_{2} & 0 & 0 \\{- S_{2}^{*}} & S_{1}^{*} & 0 & 0 \\0 & 0 & S_{3} & S_{4} \\0 & 0 & {- S_{4}^{*}} & S_{3}^{*}\end{bmatrix}}},$ where T_(ij) represents the symbol to be transmittedon the ith antenna and the jth subcarrier; determining whether thesecond burst of signal is successfully decoded; and when the secondburst of signal is not successfully decoded, softly combining the firstburst of signal and the second burst of signal to generate a combinedsignal, and decoding the combined signal by applying the first spacefrequency block code format to the first burst of signal, and applying asecond space frequency block code format to the second burst of signal,with a transmission matrix T₂ within the second space frequency blockcode format being established by: ${T_{2} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = \begin{bmatrix}S_{3} & S_{4} & 0 & 0 \\{- S_{4}^{*}} & S_{3}^{*} & 0 & 0 \\0 & 0 & S_{1} & S_{2} \\0 & 0 & {- S_{2}^{*}} & S_{1}^{*}\end{bmatrix}}},$ where T_(ij) represents the symbol to be transmittedon the ith antenna and the jth subcarrier.
 46. A wireless terminal in acommunication system, comprising: a memory unit storing a first burst ofsignal and a second burst of signal that are received within a radiosubframe; and a decoding unit decoding the received signals, with thedecoding unit: decoding the second burst of signal by applying a firstspace frequency block code format in which a transmission matrix T₁ anda transmission matrix T₂ are sequentially applied in a frequency domain,with the transmission matrices T₁ and T₂ being respectively establishedby: ${T_{1} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = \begin{bmatrix}S_{1} & S_{2} & 0 & 0 \\{- S_{2}^{*}} & S_{1}^{*} & 0 & 0 \\0 & 0 & S_{3} & S_{4} \\0 & 0 & {- S_{4}^{*}} & S_{3}^{*}\end{bmatrix}}},{T_{2} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = \begin{bmatrix}S_{3} & S_{4} & 0 & 0 \\{- S_{4}^{*}} & S_{3}^{*} & 0 & 0 \\0 & 0 & S_{1} & S_{2} \\0 & 0 & {- S_{2}^{*}} & S_{1}^{*}\end{bmatrix}}},$ where T_(ij) represents the symbol to be transmittedon the ith antenna and the jth subcarrier; determining whether thesecond burst of signal is successfully decoded; and when the secondburst of signal is not successfully decoded, softly combining the firstburst of signal and the second burst of signal to generate a combinedsignal, and decoding the combined signal by applying the first spacefrequency block code format to the first burst of signal, and applying asecond space frequency block code format to the second burst of signal,with, in the second space frequency block code format, the transmissionmatrix T₂ and the transmission matrix T₁ being sequentially applied inthe frequency domain.
 47. A wireless terminal in a communication system,comprising: a modulation unit modulating data to be transmitted by usinga certain modulation scheme to generate a plurality of modulatedsymbols; a processing unit establishing a transmit diversity scheme forat least a group of four symbols S₁, S₂, S₃ and S₄ from among theplurality of modulated symbols, with the transmit diversity scheme beingestablished such that two transmission matrices T₁ and T₂ arealternatively applied in a frequency domain, and the two transmissionmatrices T₁ and T₂ being respectively established by:${T_{1} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = {\frac{1}{\sqrt{4}}\begin{bmatrix}S_{1} & {- S_{2}^{*}} & S_{1} & {- S_{2}^{*}} \\S_{2} & S_{1}^{*} & S_{2} & S_{1}^{*} \\S_{3} & {- S_{4}^{*}} & {- S_{3}} & S_{4}^{*} \\S_{4} & S_{3}^{*} & {- S_{4}} & {- S_{3}^{*}}\end{bmatrix}}}},{and}$ ${T_{2} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = {\frac{1}{\sqrt{4}}\begin{bmatrix}S_{1} & {- S_{2}^{*}} & S_{1} & {- S_{2}^{*}} \\S_{3} & {- S_{4}^{*}} & {- S_{3}} & S_{4}^{*} \\S_{2} & S_{1}^{*} & S_{2} & S_{1}^{*} \\S_{4} & S_{3}^{*} & {- S_{4}} & {- S_{3}^{*}}\end{bmatrix}}}},$ where T_(ij) represents the symbol to be transmittedon the ith antenna and the jth subcarrier; and four antennastransmitting the four symbols S₁, S₂, S₃ and S₄ in accordance with thetransmit diversity scheme.
 48. A wireless terminal in a communicationsystem, comprising: a modulation unit modulating data to be transmittedby using a certain modulation scheme to generate a plurality ofmodulated symbols; a processing unit establishing a transmit diversityscheme for at least a group of four symbols S₁, S₂, S₃ and S₄ from amongthe plurality of modulated symbols, with the transmit diversity schemebeing established such that two transmission matrices T₁ and T₂ arealternatively applied in a time domain, and the two transmissionmatrices T₁ and T₂ being respectively established by:${T_{1} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = {\frac{1}{\sqrt{4}}\begin{bmatrix}S_{1} & {- S_{2}^{*}} & S_{1} & {- S_{2}^{*}} \\S_{2} & S_{1}^{*} & S_{2} & S_{1}^{*} \\S_{3} & {- S_{4}^{*}} & {- S_{3}} & S_{4}^{*} \\S_{4} & S_{3}^{*} & {- S_{4}} & {- S_{3}^{*}}\end{bmatrix}}}},{and}$ ${T_{2} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = {\frac{1}{\sqrt{4}}\begin{bmatrix}S_{1} & {- S_{2}^{*}} & S_{1} & {- S_{2}^{*}} \\S_{3} & {- S_{4}^{*}} & {- S_{3}} & S_{4}^{*} \\S_{2} & S_{1}^{*} & S_{2} & S_{1}^{*} \\S_{4} & S_{3}^{*} & {- S_{4}} & {- S_{3}^{*}}\end{bmatrix}}}},$ where T_(ij) represents the symbol to be transmittedon the ith antenna and the jth subcarrier; and four antennastransmitting the four symbols S₁, S₂, S₃ and S₄ in accordance with thetransmit diversity scheme.
 49. A wireless terminal in a communicationsystem, comprising: a modulation unit modulating data to be transmittedby using a certain modulation scheme to generate a plurality ofmodulated symbols; a processing unit establishing a transmit diversityscheme for at least a group of four symbols S₁, S₂, S₃ and S₄ from amongthe plurality of modulated symbols by alternatively applying twotransmission matrices T₁ and T₂ in both of a time domain and a frequencydomain, with the two transmission matrices T₁ and T₂ being respectivelyestablished by: ${T_{1} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = {\frac{1}{\sqrt{4}}\begin{bmatrix}S_{1} & {- S_{2}^{*}} & S_{1} & {- S_{2}^{*}} \\S_{2} & S_{1}^{*} & S_{2} & S_{1}^{*} \\S_{3} & {- S_{4}^{*}} & {- S_{3}} & S_{4}^{*} \\S_{4} & S_{3}^{*} & {- S_{4}} & {- S_{3}^{*}}\end{bmatrix}}}},{and}$ ${T_{2} = {\begin{bmatrix}T_{11} & T_{12} & T_{13} & T_{14} \\T_{21} & T_{22} & T_{23} & T_{24} \\T_{31} & T_{32} & T_{33} & T_{34} \\T_{41} & T_{42} & T_{43} & T_{44}\end{bmatrix} = {\frac{1}{\sqrt{4}}\begin{bmatrix}S_{1} & {- S_{2}^{*}} & S_{1} & {- S_{2}^{*}} \\S_{3} & {- S_{4}^{*}} & {- S_{3}} & S_{4}^{*} \\S_{2} & S_{1}^{*} & S_{2} & S_{1}^{*} \\S_{4} & S_{3}^{*} & {- S_{4}} & {- S_{3}^{*}}\end{bmatrix}}}},$ where T_(ij) represents the symbol to be transmittedon the ith antenna and the jth subcarrier; and four antennastransmitting the four symbols S₁, S₂, S₃ and S₄ in accordance with thetransmit diversity scheme.